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Wednesday, 13 May 2009

Putting the Heat on Coal-Fired Power Generation_ Materials, Steels, Superalloys, Coatings to fight GHG Emissions? Information overload assistance

The heat is on in more than one sense!

One of my "Wedge-a-War" aims (in the Pacala-Socolow-S.Lam sense[pdf]) deriving from my focus on CCS-CO2 capture and storage is to bring the materials issues to the fore:

To such an end, we metallurgist, students or experience metallurgical scientists and power engineering professionals alike will be much indebted to the pragmatic materials expert Prof. T.B. Gibbons for his paper entitled Superalloys in modern power generation applications, Ed. Materials Science and Technology 2009 VOL 25 NO 2. available online to IOM3 members.

The paper opens in Tom’s typically pragmatic style recalling that;
“It is widely recognised that for the foreseeable future, coal will remain an important energy source for generation of electric power in many areas of the world. [In other words we are stuck with it and must make the best of the situation.] However, it will be essential to develop generation technologies that include the capture and storage of emissions such as CO2 to combat the harmful effects of climate change.

[One of the] "The key(s) to the successful implementation of advanced generation technologies, the ultimate aim of which is the zero emission power plant, depends heavily on the availability of suitable materials." [and perhaps more importantly on the exploration and qualification of suitable geological CO2-GHG storage sites?]

In his paper, Gibbons considers the requirements for materials with improved high temperature performance, discipline in which he is a world renowned expert. He applies his expertise in the context of three types of power generation systems being developed to operate with greatly reduced emissions and with high levels of efficiency.

(i) ultra supercritical (USC) steam power plant ( steam T> 760°C)
(ii) integrated gasification combined cycle systems (IGCC)
(iii) oxyfuel combustion (Clean Energy Systems).
whose respective merits he describes and illustrates with schematics.

The common feature in all three approaches is the drive for greater efficiency of power generation systems, since this will mean that the level of emissions per unit of power output is reduced. Thus, it is claimed that a high efficiency power plant generating 500 MW of electricity will produce 27% less CO2 than a conventional plant of similar capacity. More... cf.Gibbons Ref.1

Work is in progress worldwide to improve the efficiency of power generation technologies, which use coal as a primary energy source. Such improved efficiency requires the use of higher temperatures cf. Fig.1 click to enlarge.

World Wide Programmes referenced are:

Examples of these activities are the:
-AD700Project in Europe whose acronym means ADvanced T>700°C [pdf]and AD 700 participants. and the

-Ultragen project in USA [pdf], where the aim is to build demonstration plants operating with higher steam temperatures and hence higher efficiencies, and a US Department of Energy (DoE) Project to develop more efficient coal gasification combined cycle systems.

In Japan, efforts are in hand to retrofit older coal burning units to enable operation at
higher steam temperatures with improved efficiencies. (Gibbons Ref.4)

There is a lot of metallurgy condensed in Tom’s paper, from recommended high-temperature steels, superalloys, and coatings for plant and turbine blades-aerofoils. The limitations of existing materials are outlined and the need for materials with higher temperature capabilities and ease of manufacture are discussed from a metallurgical science and engineering perspective.
The paper is an excellent summary of the metallurgical issues facing materials engineers in order to meet the challenges of so called “clean coal” and “zero emission" technologies.
Many of the papers referenced or related may be obtained, often freely available online.

In fact Tom Gibbon’s paper is a good window into a much researched field, but perhaps one where practice lags rhetoric among the main industrial... players, who admittedly suffer from the heavily capitalised, huge inertia bound (muscle-bound?), nature of the systems in which they operate?

Brain d-rain video: Frosty the coalman for a laugh (or a cry).
Comment cf. further reading ref.3 below.
Further comments, suggestions or questions welcome.

cf. reported comments section.
All 22 conference papers presented at the Malcolm McLean Memorial Symposium: “The superalloys: from processing to performance”)by internationally recognised experts in the field have been issued in a special addition of Materials Science and Technology Vol 25 Feb 2009. [almost 200 pages on all aspects of superalloy process and product metallurgy;from R&D, through primary and secondary melting, casting and single crystal growth, hot-transformation (rolling, forging etc), critical properties at high-temperatures in stressful and corrosive environments have all been addressed to meet the highest standards and client requirements and rightly claim the conference title superalloys: from processing to performance"

Further reading on this blog:

1. Renewable and Alternative Energy Sources Ranked_Review of solutions to global warming, air pollution, energy security_Information Overload Mastered

2. Solutions to global warming, air pollution, and energy security reviewed _Parametres used to classify and rank_Follows previous post

3. New comments-Conversations with B.J. Sovacool on Nuclear Power Plant, Coal Fired Power Generation, GHG emissions

Main Reference: Materials Science and Technology Vol 25 Feb 2009

High Purity Cr sources for Superalloys

Energy for th Future:Phil.Trans.A-Vol. 365, N° 1853 / April 15, 2007, curtesy The Royal Soc. London

Engineered foams and porous materials: Phil Trans A. Vol 364, N° 1838 / 06 curtesy_The R Soc. Lond